Developing and rapidly industrializing regions, faced with rapidly increasing populations as a result of high birth rates and in-migration, are battling with the accompanying environmental problems of unplanned urban growth and emerging mega-cities (those with more than 10 million inhabitants). Estimates indicate that by the year 2000, cities will fall in this category. The rise of such cities in Asia and the Pacific, Latin America, and Africa has been accompanied by the proliferation of slums and squatter settlements without access to basic infrastructure, water, or sanitation. Eastern Europe is also affected to some degree by this phenomenon, as are a number of cities in West Asia, especially those experiencing massive rural-to-urban migration.

The resultant concentration of people and of industrial and domestic effluents and waste impose unwieldy demands on urban environments. Poor urban and solid waste management in African cities is particularly problematic in view of the potentially damaging effects on human health. At the same time, there is a move in western Europe and North America toward greening cities and encouraging reduced urban population densities. The increasing number of single-person households in these latter regions, however, is placing increased demands on energy resources and the management of wastes.

Wherever management and disposal of industrial and domestic waste is inadequate, these sources of soil and water contamination pose potential hazards to human and ecosystem health. Consequently, improved waste management is a priority in urban and industrial areas of Europe. Changing consumption patterns and recycling are encouraged by governments, but thousands of contaminated sites remain due to improper waste disposal, particularly in Eastern Europe and the former Soviet Union.

Investment in new technologies is helping improve waste management in much of western Europe. In the Asia-Pacific region, rapidly growing economic activity and populations have stimulated solid and industrial waste generation to the extent that it now poses a serious environmental health problem.

In the industrializing countries of Latin America, industrial effluent and solid wastes pose increasing hazards to human health because of the close proximity of large populations to the contaminants. Waste management receives serious attention throughout North America due to the ever increasing quantities of municipal and industrial waste generated. The region is the leading producer of waste on the planet.

Chemical pollutants are emerging world-wide as a pervasive environmental concern of highest priority. Environmental emergencies involving chemicals appear to be steadily increasing, and mounting evidence is being put forth about serious health risks posed by persistent organic pollutants. Radioactive pollution remains a top environmental concern of countries in northern and eastern Europe, particularly those of the former Soviet Union.